Title
Fluctuations in superconducting rings with two order parametersFluctuations in superconducting rings with two order parameters
Author
Faculty/Department
Faculty of Sciences. Physics
Research group
Condensed Matter Theory
Publication type
article
Publication
Lancaster, Pa,
Subject
Physics
Source (journal)
Physical review : B : condensed matter and materials physics. - Lancaster, Pa, 1998 - 2015
Volume/pages
84(2011):21, p. 214515,1-214515,9
ISSN
1098-0121
ISI
000297932500004
Article Reference
214515
Carrier
E-only publicatie
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
Motivated by two-band superconductivity in, e.g., borides and pnictides, starting from the two-band Ginzburg-Landau energy functional, we discuss how the presence of two order parameters and the coupling between them influence a superconducting ring in the fluctuative regime. Our method is an extension of the von OppenRiedel formalism for rings; it is exact, but requires numerical implementation. We also study approximations for which analytic expressions can be obtained, and check their ranges of validity. We provide estimates for the temperature ranges where fluctuations are important, calculate the persistent current in MgB2 rings as a function of temperature and enclosed flux, and point out its additional dependence on the cross-section area of the wire from which the ring is made. We find temperature regions in which fluctuations enhance the persistent currents and regions where they inhibit the persistent current. The presence of two order parameters that can fluctuate independently always leads to larger averages of the order parameters at Tc, but yields larger persistent current only for appropriate parameters. In cases of very different material parameters for the two coupled condensates, the persistent current is inhibited.
Full text (open access)
https://repository.uantwerpen.be/docman/irua/f0b866/de967b7a.pdf
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